U.S. patent number 4,296,061 [Application Number 06/131,712] was granted by the patent office on 1981-10-20 for thermoplastic gob feeding and transfer method and apparatus.
This patent grant is currently assigned to Owens-Illinois, Inc.. Invention is credited to James W. Buckingham.
United States Patent |
4,296,061 |
Buckingham |
October 20, 1981 |
Thermoplastic gob feeding and transfer method and apparatus
Abstract
The invention provides an improved method and apparatus for
effecting the severing of successive gobs from a continuously
extruded rod-like formation of organic thermoplastic material,
followed by the successive transfer of the gobs to successive
molding units which are continuously movable relative to the
free-fall path of the gobs. Severing means are provided which are
operative upon a vertically extruded rod-like formation of hot
organic thermoplastic material. A plurality of molding members,
each having an open top molding cavity, are moved in timed
relationship to the gob severing means along a horizontal path
adjacent to the free fall path of the severed gobs. Each gob is
caught by a transfer device which is movable under the free-fall
path of the gobs in timed relationship to the gob severing and the
movement of the molding members. The transfer device effects the
lateral displacement of each gob deposited on its top surface and
then a stationary deflecting device moves the gob off the surface
of the transfer device and drops it into the open top molding
cavity of the moving molding members. Cooling of the transfer plate
and deflector provides an identical thermal history for each
gob.
Inventors: |
Buckingham; James W.
(Pemberville, OH) |
Assignee: |
Owens-Illinois, Inc. (Toledo,
OH)
|
Family
ID: |
22450679 |
Appl.
No.: |
06/131,712 |
Filed: |
March 19, 1980 |
Current U.S.
Class: |
264/138; 65/303;
65/304; 264/145; 264/148; 264/238; 264/297.1; 264/299; 264/309;
425/256; 425/261; 425/308; 425/447; 425/809 |
Current CPC
Class: |
B29C
31/048 (20130101); B29C 31/06 (20130101); B29C
43/06 (20130101); B29C 43/34 (20130101); B29C
48/06 (20190201); B29L 2031/565 (20130101); Y10S
425/809 (20130101); B29C 48/00 (20190201); B29C
2043/3433 (20130101) |
Current International
Class: |
B29C
31/06 (20060101); B29C 31/04 (20060101); B29C
43/06 (20060101); B29C 43/04 (20060101); B29C
47/00 (20060101); B29B 005/06 () |
Field of
Search: |
;425/215,256,258,259,447,809,261,308
;264/5,142,144,148,297,309,138,145,238,299
;65/165,303,304,325,326,334 ;198/560,803 ;83/343 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lowe; James B.
Attorney, Agent or Firm: Nelson; John R. Click; Myron E.
Wilson; David H.
Claims
What is claimed is:
1. Method of feeding a free falling gob of heated thermoplastic
material to a molding cavity comprising the steps of:
(1) intercepting the free fall of a gob with a transfer surface
that is continuously moving in a horizontal plane;
(2) moving the gob solely by the movement of the transfer surface
to a position horizontally spaced from the free fall path of the
gob, and
(3) deflecting the gob from the moving transfer surface to fall
into a molding cavity.
2. The method of feeding successive free falling gobs of heated
thermoplastic material to successive molding cavities, comprising
the steps of:
(1) intercepting the free fall of each gob with a continuously
horizontally moving transfer surface:
(2) moving each gob solely by the movement of the transfer surface
to a position horizontally spaced from its free fall path, and
(3) deflecting each successive gob from the moving transfer surface
into a molding cavity positioned below the transfer surface.
3. The method defined in claims 1 or 2 plus the step of maintaining
the transfer surface at a pre-determined temperature, thereby
imparting an identical thermal history to each successive gob.
4. A gob feeding mechanism for converting a continuously extruded
rod-like formation of heated thermoplastic material into a series
of identical weight gobs and delivering the gobs respectively to
molding members, comprising, in combination, shearing means
periodically contacting the thermoplastic formation to shear freely
falling gobs therefrom, a transfer plate mounted beneath the shear
member, means mounting said transfer plate for continuous
horizontal rotational movement intersecting the free fall path of
the gobs so that a portion of the transfer plate will periodically
receive a falling gob thereon and move said gob horizontally solely
by movement of the transfer plate, and means for deflecting the gob
from the transfer plate into a molding member at a position
horizontally spaced from the free fall path of the gobs.
5. A gob feeding mechanism for converting a continuously extruded
rod-like formation of heated thermoplastic material into a series
of identical weight gobs and delivering the gobs respectively to
molding members, comprising, in combination, shearing means
periodically contacting the thermoplastic formation to shear freely
falling gobs therefrom, a transfer plate mounted beneath the shear
members, means mounting said transfer plate for continuous
horizontal movement intersecting the free fall path of the gobs so
that a portion of the transfer plate will periodically receive a
falling gob thereon, a plurality of molding members each having an
open top molding cavity, means for moving said molding members
successively beneath the path of movement of said transfer plate
and in timed relationship to the movement thereof, and means for
deflecting each gob on said transfer plate to fall into the open
top molding cavity of a molding member passing beneath the transfer
plate.
6. A gob feeding mechanism for converting a continuously extruded
rod-like formation of heated thermoplastic material into a series
of identical weight gobs and delivering the gobs respectively to
molding members, comprising, in combination, a pair of shear
members periodically contacting the thermoplastic formation to
shear freely falling gobs therefrom, a cullet chute disposed
beneath the path of the falling gobs, a transfer plate mounted
intermediate the shear members and the cullet chute, means mounting
said transfer plate for rotation about a vertical axis so that a
peripheral portion of the transfer plate can periodically receive a
falling gob thereon, a gob discharge aperture in said transfer
plate peripheral portion, a plurality of molding members each
having an open top molding cavity, means for moving said molding
members successively beneath the path of said gob discharge
aperture and in timed relationship to the rotation thereof, and
means for deflecting each gob on said transfer plate into said gob
discharge aperture to fall into the open top molding cavity of the
molding member passing beneath the transfer plate.
7. The apparatus of claim 4, 5, or 6 plus means for cooling the gob
contacting portions of said transfer plate to maintain same at a
uniform temperature, and means for cooling said gob deflecting
means to maintain same at a uniform temperature, thereby giving
each successive gob transferred an identical thermal history.
8. The apparatus of claim 5 or 6 wherein said deflecting means
comprises a stationary element overlying the path of the gob
carrying portion of said transfer plate at a position adjacent to
the underlying path of the molding members.
9. The apparatus of claim 6 plus selectively operable means for
deflecting a gob deposited on said transfer plate into said cullet
chute.
Description
BACKGROUND OF THE INVENTION
The compression molding technique has heretofore been utilized in
connection with the molding of organic thermoplastic articles from
a heated gob of material. If only a single molding cavity is
employed, there is little problem in dropping the gob into the
cavity and effecting the compression molding of the gob; however,
when a plurality of continuously moving molding members are
employed, it is necessary that a plurality of identical gobs be
successively formed and respectively deposited in the molding
cavities in timed relationship to the arrival of the molding
cavities at the point of deposit and with each gob having an
identical thermal history. If the successive gobs of heated organic
thermoplastic material are formed by successive severing operations
on a vertically extruded, rod-like formation of such material, it
is readily apparent that the arrival of the successive gobs at a
particular horizontal plane is dependent upon the free-fall time of
the gobs. Since the heated organic thermoplastic material is
relatively tacky, there are minute differences in the severing time
of successive gobs and, even though the gob shears be actuated
according to a desired timed sequence, this provides no assurance
that the freely-falling gobs will arrive at a particular vertical
elevation in exactly the same time sequence as the shears are
operated.
There is, accordingly, a need for a gob shearing and transfer
method and mechanism which will positively deposit successive gobs
in successive molding cavities of successive continuously moving
molding members in a desired timed sequence which coincides with
the arrival of the molding members at a particular point.
SUMMARY OF THE INVENTION
The invention provides an improved method and apparatus for
effecting the severing of successive gobs from a continuously
extruded rod-like formation of organic thermoplastic material,
followed by the successive transfer of the gobs to successive
molding units which are continuously movable relative to the
free-fall path of the gobs. Severing means are provided which are
operative upon a vertically extruded rod-like formation of hot
organic thermoplastic material. A plurality of molding members,
each having an open top molding cavity, are moved in timed
relationship to the gob severing means along a horizontal path
adjacent to the free fall path of the severed gobs. Each gob is
caught by a transfer device which is movable under the free-fall
path of the gobs in timed relationship to the gob severing and the
movement of the molding members. The transfer device effects the
lateral displacement of each gob deposited on its top surface and
then a stationary deflecting device moves the gob off the surface
of the transfer device and drops it into the open top molding
cavity of one of the moving molding members. The utilization of a
transfer device driven in positive synchronism with the molding
members assures that the time of deposit and location of the
successive gobs in the successive molding cavities will not be
dependent on variations in the free-fall time of the successive
gobs. Cooling of the transfer plate and deflector provides an
identical thermal history for each gob.
It is, accordingly, an object of this invention to provide an
improved gob-shearing and transfer method and apparatus for
effecting the feeding of molding cavities of a multi-cavity
compression molding machine in a desired timed sequence.
A particular object of this invention is to provide a transfer
mechanism for successive free-falling gobs of hot organic
thermoplastic material which intercepts the gobs and effects the
transfer of the gobs in a desired timed sequence to successive
molding cavities of a plurality of molding members which
successively move past a given point adjacent to the transfer
member.
Other objects and advantages of this invention will be apparent to
those skilled in the art from the following detailed description,
taken in conjunction with the annexed sheets of drawings on which
is shown a preferred embodiment of this invention.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a schematic perspective view of a gob feeding apparatus
embodying this invention which is specifically designed for the
successive deposit of gobs of molten thermoplastic material into
successive molding cavities.
FIG. 1a is a schematic perspective view illustrating the gob
cutting step.
FIG. 2 is a schematic view, with major portions of the apparatus
removed to more clearly illustrate the driving mechanism for the
apparatus of FIG. 1.
FIG. 3 is a schematic perspective view of a portion of the
apparatus of FIG. 1 illustrating the removal of the gob from the
transfer table for deposit by free-fall into a molding cavity.
FIG. 4 is a view similar to FIG. 3 but illustrating the diversion
of a gob carried by the transfer table into a cullet chute.
DESCRIPTION OF PREFERRED EMBODIMENT
Referring now particularly to FIG. 1, a gob-serering and transfer
apparatus embodying this invention will be seen as comprising a
drive motor 10 which provides motive power for all of the moving
parts of the apparatus through gearing connections therewith,
thereby assuring the synchronous operation of the various moving
parts. The drive motor 10 provides driving power for a gob-shearing
apparatus 20 defined by a pair of co-operating rotating shear
elements 21 and 22 which have eccentrically disposed cutting blades
21a and 22a which rotate into abutting engagement and pass through
a dependent rod of heated thermoplastic material TP (FIG. 1a) which
is being continuously issued in a rod-like formation from an
extruder or any other form of feeder capable of producing a
rod-like formation of molten thermoplastic material. Thus each
rotation of the gob shearing elements 21 and 22 effects the
production of a gob G of thermoplastic material which then falls
vertically downwardly along a path coincident with line 5 onto the
horizontal surface 30a of a rotating cup shaped transfer table 30
whose periphery passes under the gob fall path. While transfer
table 30 is of generally circular form, its top surface 30a is
provided with two segment-shaped cut-outs 30b and 30c which are in
diametrically opposed relationship. Cut-outs 30b and 30c pass in
each rotation successively over the top open end of a gob chute 40
and, on the opposite side of the transfer table 30, over the open
end of a molding cavity 50a of one of a plurality of molds 50 which
are successively moved into a position of vertical alignment
beneath the path of the cut-out segments 30b and 30c and
horizontally spaced from the free-fall path 6 of the severed gobs
G.
In the normal operation of the transfer plate 30, a severed gob G
of molten thermoplastic material is deposited on the horizontal
surface 30a and moved laterally by the rotation of the transfer
table 30 to a position directly overlying the open top mold cavity
50a where it is engaged by a fixed gob transfer deflector 32 and
pushed off surface 30a to fall through either the open segment 30b
or 30c into the open top molding cavity 50a. On the other hand, if
it is desired to interrupt the deposit of successive gobs G of
molten thermoplastic material into the molding cavities 50a of the
successive molding elements 50, then a cullet scraper block 45
(FIG. 3) is lowered by a solenoid 46 into sliding engagement with
the top surface 30a of the mold transfer table 30, and this element
engages the deposited gob G as the table 30 rotates and scrapes it
off the mold transfer surface 30a to fall thru open segment 30b or
30c into the exposed upper end of the cullet chute 40.
In order to provide each successive gob G that is deposited in a
molding cavity 50a with an identical thermal history, the gob
receiving top surface 30a of the mold transfer table 30 is
maintained at a pre-determined temperature through the circulation
of a suitable cooling fluid through the hollow interior of the
rotary table 30. Additionally, the gob transfer deflector 32 is
formed of a hollow configuration and the arcuate gob engaging
surface 32a of the transfer element 32 is maintained at a
pre-determined temperature through the circulation of cooling fluid
to the hollow interior of the gob transfer deflector 32.
It is therefore apparent that the aforedescribed apparatus effects
the feeding of a freely-falling gob of heated theremoplastic
material to a molding cavity by first intercepting the
freely-falling gob with a transfer surface 30a that is continuously
moving, i.e. rotating or oscillating, in a horizontal plane. The
gob is then moved solely by the movement of the transfer surface
30a to a position that is horizontally spaced from the free-fall
path of the gob and the gob is then deflected from the moving
transfer surface to fall into a molding cavity of a mold element
that is positioned in the path of freefall 6 of the gob. All
portions of the transfer surface 30a and the deflector element 32
that contact the successive gobs are maintained at a pre-selected
temperature so that the thermal history of each gob deposited in a
molding cavity is identical, thereby assuring that the resultant
plastic articles molded in the successive molds will have no
variations attributable to differences in thermal history of the
gobs deposited in the successive molds.
A more detailed description of the elements of the apparatus shown
in the drawings will now be presented. The motor 10 providing the
motive power for the drive mechanism may be an ordinary electric
motor driven in conventional manner from a power source. In such
event, then a synchronizing clutch (not shown) will have to be
provided between the gob feeder drive mechanism and the molding
machine which governs the movement of the successive molds 50 into
a position to receive the successive severed gobs of thermoplastic
material. Alternatively, the motor 10 may be replaced by a direct
drive connection from the mechanism controlling the movement of the
successive molds 50.
An appropriate molding machine for use with the gob feeding
apparatus of this invention is described and claimed in the
co-pending application of Stephen W. Amberg and Ralph G. Amberg
Ser. No. 131713, filed concurrently with this application, and of
common ownership and reference may be had to such application for
detailed information concerning the molding apparatus which governs
the positioning of the successive molds 50 in timed and spaced
relationship to the operation of the gob severing mechanism 20.
In the apparatus shown in the drawings, the motor 10 drives a
gear-reduction transmission unit 12. Transmission unit 12 has an
output sprocket (not shown) which drives a chain 12a which in turn
drives a sprocket 12b on a horizontally disposed drive shaft 16. A
parallel drive shaft 13 is driven by shaft 16 through cooperating
gears 14 and 15. The gob shearing elements 21 and 22 are
respectively secured to the drive shafts 13 and 16.
The shaft 13 also drives a rotating plastic timing disc 112 past a
conventional proximity switch 110. Switch 110 is connected in
parallel circuit relationship with the stop-start control for the
motor 10. A magnetic button (not shown) on plastic disc 112 locates
the proper stop location of the shaft 13 to insure that when the
motor 10 is stopped, the shear blades 21a and 22a, and the transfer
table 30 are all disposed in their open positions as shown in FIG.
2, so that any additional molten thermoplastic material produced by
the extruder falls freely into the cullet chute 40.
Shafts 13 and 16 are journalled in conventional fashion by
appropriate bearing elements provided on a frame structure of the
machine which is schematically indicated by the block elements 1a,
1b and 1c respectively. Thus the gob-cutting blades 21a and 22a are
driven in synchronism and come into abutting contact once during
each rotation of the shafts 13 and 16, thereby effecting a complete
severing of a gob G from the rod-like formation TP of molten
thermoplastic material entering the apparatus from an extruder (not
shown) or similar source positioned there above.
Rotary transfer table 30 is supported for rotation by a vertical
shaft 33 which is suitably journalled by bearings (not shown)
provided in frame block 1c and is driven by helical gear 33a which
in turn is driven by helical gear 17 mounted on the shaft 16. Thus
the rotation of the transfer table 30 is in timed relationship to
the operation of the gob-shearing mechanism 20 is assured.
As previously indicated, the hollow gob transfer deflector 32 is
stationary and therefore has a bore 32c freely surrounding the
drive shaft 33. Deflector 32 is supported in a fixed angular
position relative to the drive shaft 33 by a depending L-shaped
bracket 34 which has a pronged end 34a resting on a horizontal arm
35a of L-shaped bracket 35 secured to frame block 1c by a suitable
bolt 35c passing thru vertical arm 35b. An adjusting bolt 34c
traverses the slot defined by the pronged end portion 34a and hence
permits some angular adjustment of the position of the bracket 34,
and hence of the gob transfer deflector 32, with respect to the
axis of power shaft 33. More importantly, this permits alignment of
the arcuate deflecting surface 32a of gob transfer deflector 32
directly above and preferably slightly in advance of the mold
cavity 50a of the mold 50 which is passing beneath the transfer
plate 30 in continuous motion. Hence the deflected gob G will be
moved off the transfer plate surface 30a slightly prior to the time
that the molding cavity 50a is in exact alignment with its vertical
path of fall to permit the gob to land directly in the center of
the molding cavity 50a by the further horizontal movement of mold
50 during the slight period of time required for the gob to fall
from the transfer plate surface 30a into the molding cavity 50a.
Thus the successive deposit of gobs is substantially the same
position in the successive molding cavities 50a is thereby
assured.
As previously mentioned, both the mold transfer table 30 and the
gob deflector 32 are of hollow configuration to permit the
circulation of a coolant fluid therethrough. The mechanism for
effecting such circulation is entirely conventional and hence has
not been specifically illustrated in the drawings. Naturally, a
source of cooling fluid must be provided as well as a conduit for
removing the heated fluid after it has passed through the hollow
interiors of the gob transfer element 30 and the gob deflector
element 32.
In the event it is desired that no gob be deposited in the molding
cavities to permit repair or adjustments of the molding machine, a
solenoid or fluid actuator 46 is energized by manually closing a
switch (not shown) in an appropriate electrical circuit and this
effects the lowering of cullet scraper block 45 into contact with
the top gob receiving surface 30a of the gob transfer plate 30. The
position of the scraper block 45 is directly over the open upper
end of a cullet chute 40 and hence, each deposited gob G contacts
the curved edge 45a of the scraper block 45 and is shifted by the
scraper block to fall thru the segment opening 31a or 31b, as the
case may be, thence to fall into the cullet chute 40, which
transfers the gob of thermoplastic material to a suitable cooling
and collecting chamber from which it may be subsequently re-claimed
and re-used.
Modifications of this invention will be readily apparent to those
skilled in the art and it is intended that the scope of the
invention be determined solely by the appended claims.
* * * * *